Cutting drum for coal-cutting machines



June 13, 1967 P. GUILLON ETAL 3,325,219

CUTTING DRUM FOR COAL-CUTTING MACHINES Filed Nov. 29, 1966 4 Sheets-Sheet 1 INVENTORS Pierre Guii Ilon & Alfred Vulunfln Kim; SQ Flo: vs;

ATTORNEY June 13, 1967 P. GUILLON ETAL 3,325,219

CUTTING DRUM FOR COAL'CUTTING MACHINES Filed Nov. 29, 1966 4 Sheets-Sheet 2 'M [4 GA 25 ATTORNEY June 1967 P. GUILLON ETAL.

CUTTING DRUM FOR COAL-CUTTING MACHINES 4 Sheets$heet 5 Filed Nov. 29, 1966 v INYENTORS Pierre Gulllon a Alfred Valentin ATTORNEY BY kambgfil'ucm June 13, 1967 P GUILLON T 3,325,219

CUTTING DRUM FOR COAL-CUTTING MACHINES Filed Nov. 29, 1966 4 Sheets-Sheet 4 INVENTORS Pierre Guiillon 8 Alfred Valentin BY \(am. (.3. F'CocKS m ATTORNEY United States Patent 6 3,325,219 CUTTING DRUM FOR COAL-CUTTING MACHINES Pierre Guillon, Paris, and Alfred Valantin, Clement, France, assignors to Charbonnages de France, Paris, France, a public institution of France Filed Nov. 29, 1966, Ser. No. 604,518 Claims priority, application France, July 23, 1963, 942,413 11 Claims. (Cl. 299-89) This application is a continuation-in-part of application Ser. No. 384,098, filed July 21, 1964, and now abandoned.

Studies carried out by the inventors have made is possible to understand more fully the very special evolution of the forces developed by a pick cutting coal or ore to deepen a cut. It has been found that the forces are such as would 'be measured if the cutting were carried out in a single pass from the free surface of the material, of a groove of the same total depth as that obtained by the deepening cut. This fact is still valid in the case where two adjacent cuts are separated by a step or ridge of uncut material.

The studies referred to were directed (a) to the maximum spacing of the picks so that no ridge is left between their tracks; (b) to the number of picks to be utilized in order to produce furrows; and (c) to the minimum width to be given to the furrows.

It will be observed that on cutting machines, the adjacent picks follow each other at a relatively great distance, which leads to the thought that in practice the stresses developed in the material by one of the picks have no influence on the conditions of working of the following picks.

It is know-n that the ridge becomes sutficiently fragile to be broken-up by the passage of the pick making the next adjacent cut when the ratio of its height to its width is greater than 1.5 in the case of hard rock and in the vicinity of 1 for soft rock.

For example, with picks having a cutting head of 16 mm. in width, the ridge is fragile if, for a height of mm., its width varies from 10 to 6 mm. (or the distance between centers of the picks varies from 26 to 22 mm.) depending on the rock.

Now we have found that:

(a) The pass depth has an influence on the minimum width to be given to the furrow.

Thus for a pass of 7.5 mm. in depth, the furrow must have a minimum width of 35 to 40 mm. in order that picks of 16 mm. do not work in repeated depth-cutting.

('b) A minimum of three picks is necessary to make a furrow without encountering repeated depth-cutting.

The invention is based on the above findings, and consists of a new type of cutting drum comprising a plurality of picks arranged in groups, the distribution of picks in a group being such that the tracks left by the picks in the rock are sufficiently close to provide in their vicinity a substantially plane surface.

The new drum according to the invention is a result of the combination of the following features: it comprises groups of at least three picks; along the axis of rotation of the drum, the extremities of the picks of the same group are spaced apart from each other by a distance substantially equal to the width of the said picks; the different groups of picks are spaced apart from each other, along the axis of rotation of the drum by a distance of the order of the width of one group, a hollow space being thereby formed between the supports of two adjacent groups, the width of the hollow being less than, or, at the most, equal to its depth.

In accordance with further characteristic features: in

the case where the picks of the same group are distributed in radial planes spaced apart from each other, the lateral picks are set back along the drum axis with respect to a plane normal to the drum axis containing the central pick by an amount which increases with theamount of their retard in the direction of rotation of the drum, with respect to the said central pick; two picks, also spaced apart from the central plane of the furrow cut by the picks of the group to which they belong, have their extremities on the same cylinder coaxial with the drum, and are located in adjacent radial planes; the pick supports have a shape so designed as to pass in the track of the group of picks; the supports are substantially of the same length.

According to an advantageous form of construction: each set of picks is distributed on two diametricallyopposite supports, one carrying the central pick or picks and the other carrying the other picks of the group; the supports are displaced with respect to each other along a helix formed on the surface of the drum.

Other particular features and advantages of the invention will be brought out in the description which follows below with reference to the accompanying drawings, in which:

FIG. 1 is an elevational view of a drum according to the invention;

FIG. 2 is an end view of the drum;

FIG. 3 illustrates the positions occupied by the various groups of picks during the course of rotation of the drum, without advancing;

FIG. 4 is an end View of the drum represented in FIG. 3;

FIG. 5 is a diagram showing the distribution of the picks of one group; and

FIG. 6 is a diagram of the tracks cut by two adjacent groups of picks.

In the description which follows, the term cut is used to represent the track left by a pick in the solid mass to be cut and furrow represents the track left by a group of picks. The same indices have been given to the cuts and to the picks which have cut them.

The order in which the picks of one group attack the material is indicated by the successive figures 1, 2, 3, 4 given to the indices by which they are designated.

FIGS. 1 and 3 show diagrammatically a construction of drum according to the invention. In the case of these figures, the drum has already penetrated into the solid mass to be cut, designated by the reference 0.

The drum is composed of a cylinder 1, the axis of rotation of which is XX and on the surface of which are arranged pick supports, the thickness of each pick support being less than the width of the furrow out by the group of picks including the picks supported by said each pick support.

The pick supports are arranged in sets of diametrically opposed pairs, with each pair lying in a plane normal to the axis XX. The plane of symmetry of each group is the plane of symmetry of the furrow cut by all of the picks of the group supported by a pair of oppositely disposed pick supports. While this preferred construction has been illustrated in the attached drawings, the group of three or more picks may be arranged on a single support, or on more than two supports. Thus, a set of supports may comprise one or more supports. Each of the supports of one pair carries part of a given group of picks.

There are thus the two pairs of lateral supports A1- A2 and Dl-D2, of which the respective planes of sym- -metry are P1 and P4, and the two pairs of central supports Bl-BZ and C1C2, the respective planes of symmetry of which are P2 and P3.

All the supports have substantially the same radial length. This length is such that the distance from the extremities of the picks to the surface of the drum is from 1 to 1.5 times the distance between two adjacent supports, measured along the drum axis, in the case of soft to medium hardness material, and may be as much as 2 times that distance for hard material.

The supports are arranged on the surface of the drum in such manner as to follow two diametrically-opposite helixes traced on the surface of the cylinder.

The picks are in groups of four picks each (two central picks and two side picks) and are distributed as follows:

(A) The central picks of each group are carried by a support and are arranged in line following one of the helixes; thus, the picks 1A and 2A (see FIG. 3) are carried by the support Al, the picks 1B and 2B by the support B1, the picks 1C and 2C by the support C1, and the picks 1D and 2D by the support D1.

(B) The side picks of each group are carried by the supports in line along the helix diametrically-opposite to that mentioned above, namely, the picks 3A and 4A are carried by the support A2, the picks 3B and 4B by the support E2, the picks 3C and 4C by the support C2, and the picks 3D and 4D by the support D2.

Referring now to FIG. 4, the extremities of all the central picks are located at the same radial distance x from the axis XX of the drum; the extremities of all the lateral picks are located at the same distance x from the axis XX; x is greater than x and the set-back distance x: (x x is a function of the advance movement provided for the drum.

The groups of picks produce, respectively, the furrows GA, GB, GC and GD. Two adjacent furrows leave a ridge of uncut rock such as AA, BB or CC.

As will be seen herein below, the ridges break up at their base along the line of fracture represented by the double continuous lines.

FIGS. 2 and 4 show diagrammatic side views of the above-mentioned drum disengaged from the solid mass to be cut, the arrow F indicating the direction of rotation of the drum about its axis XX, the location of which is the point I. It will be observed that the picks such as 1A and 2A, located in adjacent radial planes, have their extremities at equal radial distances from axis XX, while picks such as 3A and 4A, located in radial planes next to each other and spaced apart from radial planes of 1A and 2A, have their extremities at a radial distance from axis XX which is different from the preceding distance. In the general case, the amounts by which the picks are set back are a function of the advance provided for the drum and of their retard in rotation with respect to a given reference pick.

The pick 3A, placed behind the pick 3A and in the same plane normal to the axis XX, has its extremity at the same radial distance as the extremity of the pick 3A (because the two picks are located in two adjacent radial planes). Its function is to replace the pick 3A if this becomes broken under the load which is applied to it.

The radial arrangement of the picks of one group corresponds to the conditions which have been discovered by the inventors. FIG. 5 provides an illustration of this for relatively hard rock. There has been shown in full lines the position of the central picks of a group of picks at the beginning of a revolution, without advance of the drum, and in broken lines the positions of the lateral picks of this same group after one half-revolution of the drum. In conformity with the laws of repeated depth cutting, there are provided:

(1) A distance q between the pick centers (at the pick extremities) approximately no more than twice the width e of the said picks, i.e.,'pick spacing at the pick extremity is about equal to pick width.

(2) A number of picks for a width E of a furrow such 4 as GA, which is a function of the forward movement of the drum and of the width e of the picks employed.

FIG. 6 provides an explanation of the phenomenon of rupture of the ridges. The picks 1A, 2A, 3A and 4A leave existing at the bottom of the furrow GA, small ridges having a width 1: (q-e) and a height 11. When the ratio 11/! is equal to 1.5 (or at least equal to 1 if the rock is soft), these ridges become broken-up in the course of a given pass by the force applied by the side faces of the picks in the vicinity of their heads, i.e. their working extremities.

The ridge AA which is left between the furrows GA and GB having a width R=(QE) and a height H, becomes fragile when the ratio H/R is greater than 1.5 (or at least equal to 1 if the rock is soft). Otherwise stated, for soft rock, the ridge AA is fragile and will shear at its base if it has a height equal to its width; for hard rock, the ridge is fragile and will shear at its base if it has a height greater than its width, up to a ratio of twice the width being required in some hard rock. For rock of intermediate hardness, the ratio H/R may be approximately 1.5. Shearing of the ridge is caused by lateral force applied to its side face, as by a pick support or by a side surface of the pick. These side forces are caused by lateral movements of small amplitude resulting from the inherent vibrations present in the machine as it works.

In order to facilitate the breaking-up of the ridges and to obtain a better evacuation of the products out by the picks, an arrangement of the supports such as shown diagrammatically in FIGS. 1 and 2 is provided. The pairs of supports are arranged along two helixes traced on the drum, the pitch of the helix being chosen so as to evacuate the cut products into the conveyor (not shown) mounted on the right-hand or left-hand side of the drum.

Tests with a drum according to the invention show that the distribution of the picks such as described above enables the power to be applied to the machine to be reduced for a given advance and that in consequence, larger advances can be obtained with a given machine.

It is within the scope of the invention to modify the distribution of the supports on the drum, the number of supports per group of picks (it is, for example, possible to provide four supports uniformly distributed round the drum), the relative positions of the picks in the group, the shape of the supports, etc. The invention can be applied to all kinds of forms of construction of the drum, the solid cylinder and also the details of construction having been given only by way of explanation and not in any limitative sense.

What is claimed is:

1. A cutting drum for coal cutting machines or the like comprising a cylinder adapted to rotate on its longitudinal axis,

a plurality of sets of pick supports at the outer surface of said cylinder, said sets of supports being regularly distributed about the periphery of said cylinder,

a group of at least three equal width picks on each set of supports, said group having a median plane perpendicular to said longitudinal axis, the extremities of the picks of said group being spaced apart from each other by a distance substantially equal to the width of one pick, two adjacent groups of at least three picks being spaced apart from each other along the axis of rotation of said cylinder by a distance approximately the width of one group,

the distance of the pick extremities from the cylinder surface being at least equal to the distance measured along the drum axis between adjacent sets of pick supports.

2. The cutting drum of claim 1, the distance of the pick extremities from the cylinder surface being greater than the said distance between longitudinally adjacent sets of supports.

3. The cutting drum of claim 1 wherein each said group of picks comprises at least two lateral picks and at least one central pick, all the picks of the same group being distributed in radial planes spaced apart from each other.

4. The cutting drum of claim 3, said lateral picks being set back with respect to said central pick by an amount which increases with their retard in the rotation of the drum with respect to said central pick.

5. The cutting drum of claim 1, comprising in each group of at least three picks, two picks equally spaced apart from the central plane of the group to which they belong and equally extending from their support member, said two picks being located in adjacent radial planes.

6. The cutting drum of claim 1 wherein said supports are of substantially the same length.

7. The cutting drum of claim 1, there being at least two pick supports in a set of supports, a set being supports in a common plane perpendicular to the cylinder axis.

8. The cutting drum of claim 1, each said set comprising two diametrically opposed pick supports, the supports of each set lying in a plane normal to the cylinder axis.

9. The cutting drum of claim 8 wherein each group of at least three picks comprises at least two lateral picks mounted on one support of the set of two supports and one central pick mounted on the second support of said set.

10. The cutting drum of claim 8 wherein said supports of successive sets are displaced with respect to each other along a helix on the surface of said cylinder.

11. The cutting drum of claim 1, said supports being helically positioned on said cylinder.

References Cited UNITED STATES PATENTS 318,962 6/1885 Crump et a1 299-89 X 2,710,179 6/1955 Cartlidge 29989 2,758,826 8/1956 Paget 29987 X ERNEST R. PURSER, Primary Examiner. 

1. A CUTTING DRUM FOR COAL CUTTING MACHINE OR THE LIKE COMPRISING A CYLINDER ADAPTED TO ROTATE ON ITS LONGITUDINAL AXIS, A PLURALITY OF SETS OF PICK SUPPORTS AT THE OUTER SURFACE OF SAID CYLINDER, SAID SETS OF SUPPORTS BEING REGULARLY DISTRIBUTED ABOUT THE PERIPHERY OF SAID CYLINDER, A GROUP OF AT LEAST THREE EQUAL WIDTH PICKS ON EACH SET OF SUPPORTS, SAID GROUP HAVING A MEDIAN PLANE PERPENDICULAR TO SAID LONGITUDINAL AXIS, THE EXTREMITIES OF THE PICKS OF SAID GROUP BEING SPACED APART FROM EACH OTHER BY A DISTANCE SUBSTANTIALLY EQUAL TO 